Popham D L, Szeto D, Keener J, Kustu S
Department of Microbiology and Immunology, University of California, Berkley 94720.
Science. 1989 Feb 3;243(4891):629-35. doi: 10.1126/science.2563595.
The nitrogen regulatory (NtrC) protein of enteric bacteria, which binds to sites that have the properties of transcriptional enhancers, is known to activate transcription by a form of RNA polymerase that contains the NtrA protein (sigma 54) as sigma factor (referred to as sigma 54-holoenzyme). In the presence of adenosine triphosphate, the NtrC protein catalyzes isomerization of closed recognition complexes between sigma 54-holoenzyme and the glnA promoter to open complexes in which DNA in the region of the transcription start site is locally denatured. NtrC is not required subsequently for maintenance of open complexes or initiation of transcription.
肠道细菌的氮调节（NtrC）蛋白可与具有转录增强子特性的位点结合，已知该蛋白通过一种含有NtrA蛋白（σ⁵⁴）作为σ因子的RNA聚合酶形式（称为σ⁵⁴ - 全酶）来激活转录。在三磷酸腺苷存在的情况下，NtrC蛋白催化σ⁵⁴ - 全酶与谷氨酰胺合成酶（glnA）启动子之间的封闭识别复合物异构化为开放复合物，其中转录起始位点区域的DNA局部解链。随后维持开放复合物或启动转录并不需要NtrC。
